Spark plug



March 6, 1934. v H. D. DE LONG SPARK PLUG Filed Dec. 30. 1932 Patented Mar. 6, 1934 UNITED STATES PATENT OFFICE SPARK PLUG City, Mo.

Application December 30, 1932, Serial No. 649,651

4 Claims.

This invention relates to improvements spark plugs for motor vehicles.

The primary object of the present invention is .to provide a spark plug having the usual shell, porcelain body and central electrode wherein the lower part of the porcelain body is replaced by a metal sleeve terminating at its lower end in a ball head. through which the electrode passes,

whereby the life of the plug is prolonged by reason oi the fact that the usual thin lower end of the porcelain body is replaced by a material whichwill not crack or otherwise disintegrate.

Another object of the invention is to provide a plug of the above described construction which causes a more eiilcient operation of the engine in which it is used becauseof the fact that the metal sleeve surrounding the lower end oi the electrode becomes heated to such an extent that carbon particles will notdeposit in the plug but will be entirely consumed, thereby making unnecessary the usual periodic cleaning of the plug body.

Still another object of the invention is to provide a plug wherein the central electrode encasing sleeve and the ball tip which forms a part thereof is formed of a non-expansible alloy which facilitates its application to the central electrode and insures its retaining its position thereon while the plug is in use.

A still further object of theinvention is to pro-.

vide a plug in which the central electrode encasing sleeve and the ball which forms an integral part thereof is formed of an alloy which will not melt or burn away under the excessive heat to which the plug is subjected.

The invention will be best understood from a consideration of the following detailed descrip tion taken in connection with the accompanying drawing forming part oi this specification, with the understanding, however, that the invention is not confined to any strict conformity with the showing 01' the drawing but may be changed or modified so long as such changes or modifications mark no material departure from the salient ieatures oi the invention as expressed inthe appended claims. In the drawing: Figure 1 is alongitudinal sectional view through a spark plug constructed in accordance with the present invention: Figure 2 is a bottom plan view of the same.

Referring now more particularly to the drawing wherein likenumerals of reference indicate corresponding parts throughout the several views; the numeral 1 indicates generally the shell 55 portion or the plug embodying the present inthrough the porcelain is one-third bronze, one-third brass and one-third vention which, as shown, is of the usual construction, having the interiorly enlarged upper portion 2 and the lower sleeve portion 3 which is exteriorly threaded as indicated at 4 for engagement in the threaded opening in the top of no an engine cylinder.

The numeral 5 indicates the porcelain inner body of the plug which adjacent its lower end is enlarged as indicated at 6 and positions within the enlarged upper portion 2 of'the shell, seatus ing upon the usual gasket 71 This porcelain body in the present plug structure extends only a short distance below the gasket 7 as indicated at 8 instead of continuing downwardly through the sleeve 3 as in the usual plug constructio The porcelain is held in position in the shell by the collar 9 and extending longitudinally the central electrode 10 which at its upper end is connected with the cap 11 and receives the wire holding tip 12.

The lower end of the central electrode 10 extends downwardly through the lower portion 3 of the plug beyond the lower end 8 of the porcelain and terminatesadiacent the grounded electrode 13.

Surrounding the lower end of the central electrode 10 is a tapered metal sleeve 14 which terminates at its lower and constricted end in a ball head 15. This sleeve fits tightly upon the central electrode and the upper end, which is of approximately the same diameter as the terminal portion 8 of the porcelain, abuts against a mica washer 16 which in turn bears against the terminal portion .8 in the manner shown.

The sleeve 14 and the head 15 which is integral therewith is prepared from a special alloy made up of the metals brass, red aluminum and bronze. These metals are employed in. the proportions of red aluminum which'in turn is composed of equal 05 parts of tin, red brass and aluminum. This alloy has the property of remaining uneiiected by the heat developed in the combustion chamber of the engine as regards expansion and contraction and will not melt or pit at such temperature. The sleeve will, therefore, retain its posltion upon the lower end oi the electrode and will not come on or the same and as a result 01 this and the fact that the alloy will not burn out, the life or the vplug will be materially greater than that. of other plugs which rapidly break down from various causes such, for example, as the burning away of the electrode, the lncrustation of the inner surface by carbon and the 110 breaking or cracking of the lower end or the porcelain center body as a result of the shocks received thereby from explosions in the engine chamber. The sleeve 14 will be unailected by these shocks and in addition the alloy will become highly heated and will hold the heat so that any carbon particles entering the lower sleeve portion 3' of the plug will be immediately burned up.

Because 'of the peculiar nature of the center electrode encasing sleeve which results in it becoming extremely hot and holding its heat it is possible, after the engine in which the plug is used has once been started, to continue its 'operation without using electric current to form a spark as the charge will be ignited by the heated electrode.

From the foregoing it will be readily apparent that a spark plug constructed in accordance with the present invention will have a materially greater life than plugs of the character at presentinuseandinaddition tothisitsuseinan the lower end 0! the shell, and a sleeve encasing the lower end of said electrode and at one end abutting the central non-conducting body, said sleeve being formed of an electricity conducting material which attains and retains a relatively high degree oi heat.

2. A spark plug, comprising an outer shell havv a point adjacent the end of the sleeve, and a metal sleeve surrounding the end of the electrode in the first mentioned sleeve and having a ball formed at its lower end, the said sleeve being of gradually increasing diameter from the point of connection thereoi with the ball to its opposite end which abuts the inner end of the said body.

3. In a spark plug having an outer shell body formed at one end for insertion intoan aperture in a wall 015- an engine cylinder, a body formed 0! material non-conductive of electricity and having one end extended into the shell and terminating therein adjacent the transverse center thereof, an electrode within the shell comprising an elongated body formed in the shape of a ball at one end and being of gradually increasing diameter from the ball to the other end and having the said other end abutting the central, body and be attached the said ilrst mentioned portion of the; central terminal being formed of the metals bronze, red aluminum and brass.

4. In a spark plug, a shell, a body at insulation in the shell, and a central electrode passing through said body of insulation having aterminal portion formed oi the metals bronze, red aluminum and brass. 1 HARRY D. D2; DONG.

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